Yes, it is another name for the Twashta Kasar community of Marathi brahmins
No, Khairnar is not Brahmin Surname. It is Marathi Surname.
Yes Vaidya is Marathi Brahmin surname, but found in other castes too
No it is not.
No, it is a Maratha surname (Kshatriya).
Yes.
Yes. This some Deshastha Marathi brahmins hold surname Bhandari
Thenge is a common Marathi surname that belongs to the Maratha caste, which is traditionally a warrior caste in Maharashtra, India.
Deshastha Brahmin
No, it is a Bania/Vani surname, meaning it is a Vaishya surname.
The Surname Tatwawadi in Marathi are Hindu Brahmin (Deshastha).
Marathi Surname "Keskar" belongs to Dhangar caste as well as Brahmin caste.